1. Field of the Invention
The invention relates to a bogie for a railway vehicle.
2. Description of the Prior Art
In a known bogie of the initially named type, the wheel sets are guided via two pairs of longitudinal links arranged at the two longitudinal sides of the bogie, each of which is pivotally connected to one of the axle housings. The longitudinal links are pivotally connected pair-wise in opposite senses to a coupling shaft transversely arranged on the bogie frame. The wheel sets are coupled to one another in opposite senses by the longitudinal links in the sense of passive radial self-steering (SLM-Druckschrift "Typenfamilie der Lok 2000", 1992 by Georg Siemens Verlagsbuchhandlung, in particular page 6). When travelling around a curve, the wheel sets of the known bogie are oriented approximately radially in the sense of a bending movement, i.e. pivoted through equal and opposite rotation angles about their vertical axes with respect to the position assumed during movement in a straight line. The steering angles are essentially determined by a preset stiffness to bending between the wheel sets. At the same time the oppositely directed coupling counteracts a shearing movement of the wheel sets. Using the known arrangement, a good behavior of the bogie in curves can generally be achieved which is determined, on the one hand, by the radius of curvature of the particular track section to be travelled along and, on the other hand, by the dynamic forces arising during operation and acting at the level of the tracks.
Such bogies are generally provided with damping means which act counter to the oppositely directed setting of the wheel sets in the interest of a desired operating stability so that the wheel sets are oriented at an angle of rotation deviating from the ideal radial orientation. This can lead to a deterioration of the running behavior in curves under certain operating conditions. For example, when travelling along stretches with numerous curves each having a small radius of curvature, increased forces and a corresponding wear between wheel and track must be taken into account. Under other operating conditions, in particular when large free lateral accelerations bG acting at track level arise, such as when travelling slowly along super-elevated curves (bG=approx. -1 m/s.sup.2), or for trains with inclinable car bodies travelling rapidly around track curves (bG=approx. +2 m/s.sup.2), the above-described ideal guidance of the wheel sets can either not be achieved by the known embodiment or not achieved to an adequate degree. This is due to the relatively large centrifugal forces arising under these running conditions that can lead to the wheels running up against the tracks and thus to a transmission of corresponding lateral forces through wheel flange contact, as well as to an unequal distribution of the centrifugal forces over the reaction forces between wheel and track.